4½ Digit loop-powereD meters
2
WARNING:
If any of the following operations are performed in
hazardous areas, all appropriate hazardous area procedures must
be followed.
WARNING:
Disconnect from supply before opening.
Keep cover tight while circuits are alive. Conduit seals must be
installed within 18″ of the enclosure (PD677).
AVERTISSEMENT:
Ouvrir le circuit avant D’enlevel le couvercle
garder le couvercle bien fermé tant que les circuits sont sous
tension. Un scellement doit êntre installe à moins de 450 mm du
boîtier (PD677).
WARNING:
Calibration of the Loop-Powered Display should be
performed in a non-hazardous area prior to installing it in its
enclosure.
CAUTION:
Care should be taken to avoid static electricity damaging
the electronic circuitry.
setUp
The only tools needed for calibration are a calibrated current source, a flat
head screwdriver & a phillips head screwdriver. Please note that the meter
must be disassembled in order to perform the setup functions.
Disassembly
The calibration controls are located behind the display faceplate. To
access these controls, you must first remove the enclosure cover and
faceplate by doing the following:
PD675: Loosen the four screws on the enclosure cover and remove.
Unscrew the two fasteners that hold the faceplate, then remove.
PD677: Turn the enclosure cover counterclockwise to remove. Unscrew
the two fasteners that hold the faceplate, then remove.
Display Faceplate
Display Board
Signal
Input Board
Pollution Degree 2
Installation Category II
Figure 1. PD677 Assembly
Note: When reassembling boards DO NOT over-tighten screws.
Connections
Field connections are made to the screw terminals located on the Signal
Input Board. To access these screw terminals it is necessary to remove
the Display Board from the Signal Input Board. First, disconnect the
ribbon cable connector from the Display Board. Next, remove the two
screws located to the left and right of the LCD that hold the Display
Board in place. Finally, remove the Display Board carefully to avoid
contact with any rough surfaces.
J1
Input
4-20 mA
Transmitter
Loop Power
Supply
n
Figure 2. Signal Input Connections
Calibration Controls
Calibration of these meters is a two-step process involving four controls.
These controls are located on the Display Board. The LO controls are on
the right and the HI controls on the left. The pre-configured jumper array
JP2 and JP3 are also located on the Display Board.
Calibration procedure
Connect the 4-20 mA input signal. Apply 4 mA to the input and adjust
the coarse and fine LO controls for the desired reading. Next apply a
signal between 16 and 20 mA and adjust the coarse and fine HI controls
for the desired reading. Complete the calibration by making any minor
adjustments to the LO and HI displays.
Jumper positions
JP2
JP3
JP1
1
2
3
4
Cable
1999.9
F-HI-C
C-LO-F
R24
Figure 3. Display Board
Balance Potentiometer (R24) is preset at the factory
Decimal point selection
Decimal point selection is accomplished using JP1 located behind the
faceplate to the right of the display. Leave jumper on one pin only for a
display of 19999 (default), place the jumper over both pins of #1 for a
display of 1999.9, #2 for 199.99, #3 for 19.999, #4 for 1.9999
JP1
1
2
3
4